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THAT a system of logical principles of a science so interesting to human happiness as that of medicine should not have hitherto been formed, by which the study of it might be reduced to methodic order, rather than, as is the case, pursued in a more or less irregular and indeterminate way according to the disposition of each individual, is a circumstance that may appear extraordinary to persons who have not contemplated this subject in a sufficiently accurate and comprehensive manner. In order to place it in its proper point of view, we should first determine what it is that constitutes the logic of a science, and how the logical principles of other sciences have been formed ; for, it should be understood, physics, as well as metaphysics, may each have their system of logic. > , Poetry and music preseut themselves as well adapted for the illustration of this enquiry. Above twenty ages have elapsed since their logical principles were instituted, and the same principles have maintained their original authority down to the present period, amidst all the ^evolutions of human sentiments,, under the different social and political customs and habits that have intervened.
The man of pre-eminent genius, who has collected from any objects the most accurate and comprehensive series of ideas, the mutual relations of which he has also determined, has acquired a system of knowledge of such objects that must be considered relatively perfect. To trace those ideas and the order in which, he has acquired and developed them, must, then, display all that is known respecting the subjects of them, and at the same time show the method by which such knowledge may be moit 302 Critical Shiah/six. accurately and readily obtained: it is this, we think, which constitutes the ifrgic t)f &i&c>reufce* ......

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From this view of logic, it must be evident that knowledge must be obtained, before the principles best adapted to direct liren in general in its a-cqftisitioircfm be iitstittjtfed. Sffdi has been the fact with to poetry and -music.
Homer had acquired the most perfect series of ideas of the gW)d and beautiful, the iOxKo-x.a.ykiov,' of poetical seiYthnfctfts,' Wore a systera of Poetics was formed: Aristotle onty 'dfes^fi^i the course taken by Homer? Eumpides had impressed thetiviitd of man with the most vivid feelings of awe and astonishment, before Longinus could have written his treatise on the Sublime.
ft was the same with respect to Musk. The t~ar (if Prf'ftA-1 feftliAs had enabled his tnind to discfern the relations existing between certain sounds, before he applied the relations of numbers to them to explain the nature of harmony.
If this notion be correct, and further illustrations of it tni^ht be readily adduced, but little need be said to show ivhy logical principles have hot hitherto been instituted respecting medical s<jienc&. < , ?

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Our ideas of th& physical, or rather the mechanical, fcorrstrut:-tion>of the human body, may perhaps be sulfitifctttily accurate and comprehensive for such & purpose \ but the pd^'foiogy of k: is yet obviously vef)' far from being in so perfects and its pathology is still teas advanced, although this wa& cultivated in a correct maimer at a, very remote era* Bwt subseq^uent en- %V.ith,out a.n Aiustqtle having been produced. The hope, then, that a system of medical logic will be ever instituted, must be but ver}' faint; or, at least, the probability of its realization must be assigned to far distant ages. This onjy exists for the present generation,?to proceed steadily in thetrue road for the acquisition of knowledge, which we nave at length happily discerned. We shall thus have the gratification of employing our taleuts in a manner the most immediately beneficial to human, nature; and we shall at the same time bp collecting materials adapted for the construction of an edifi.ee, that would constitute the most glorious and useful work ever executed t>y man.
Such are o.uf opinions respecting medical logic in the most comprehensive view ; but, whilst the study of the science of medicine* is parted into the divisions we have enumerated, it may perhaps be allowable, to consider the development of the principles of each;of those divisions in an isolated state, as well as it can be effected, as the logic of those divisions: and this appears tp be the opinion of Sir Gilbert Blane; for, if the work we are about to take into particular consideration ma^r .W.ith propriety be, termed " Elements of Medical Ipgidi? it sai) only be so in the partial manner we have just described, In an, analytical report of a work of this kind, the, most clear and useful method, would be, first, to give a general scope erf tjie auibor's design, and. then to.iidduce th,e; particular Ulustra.tjpn of, his principles; but, for-reasons,which will be hereafter 504 ? Critical Analysis, apparent, we must on this occasion commence with particulars, following the author step by step in his own course.
Sir Gilbert Blane commences the introduction to this Work with a definition of medicine: he says, " As medicine has for its object the preservation and restoration of health, it comes under the definition of an art,?a term, the import of which consists in the adaptation of means to ends. Tbese means must be derived from the previous knowledge of the changes producible by them, whether as corporeal agents constituting physical causes, or as affections of the mind constituting moral causes." This we consider to be only a partial view of medicine, using that term in the comprehensive sense in which it is generally received, and in which the author has himself employed it, making it to comprise physiology and pathology, as well as; therapeutics. That the two former are objects of science, must, we think, be admitted. To show this, let us consider the case of a man who has a portion of the integuments of the skull Separated from that bone by a sharp-cutting instrument, without any forcible concussion of the subjacent parts: some days afterwards symptoms of disorder of the functions of the brain 'appear; the man soon dies; dissection after death shows signs of a diseased, and perhaps gangrenous, state of the membrane lining the skull internally, corresponding in situation with that portion of it from which the external integuments had been removed. The description of these things constitutes only natural history, and the knowledge of their occurrence cannot properly be termed science (in the received meaning of that term); but, the explanation of the relation of one of these things to the other,?that is, the explanation of the causes of the results, by showing that a due circulation of fluids in a part is necessary for its vitality; that the internal membrane of the skull is chiefly dependant on the external membrane for the supply of those fluids, which is effected by the immediate transmission of vessels through that bone from one surface to the other; and, consequently, that the separation of the external integuments from the skull, by depriving the internal membrane of the fluids necessary. for its vitality, must be followed by the death of the latter. This constitutes science, just as certainly as the explaining why, in a right-angled triangle, the square of its hypothencuse is equal to the square of the two other sides. And, though the object of this knowledge is the application of medicinal agents to the cure of disease, yet the faculty of using those agents with precision cannot be acquired without this kind of knowledge. For example, a person has a disease of the hipjoint, but no uneasiness is felt in the region of that part; the pain is confined to the knee: the practitioner, following the indications of art solely, would here apply his remedy'to the Sir Gilbert Blanks Elements of Medical Logick. 305 apparent seat of the disease in vain. Science here becomes necessary, as well as art. We think they cannot be separated in a general and comprehensive definition of medicine.
Sir Gilbert Blane next adduces a statement of what he considers to constitute reason : he says, M The most precise criterion that can be fixed upon for distinguish-^ tag rational beings from brutes, is the faculty of adapting means to ends; and there is perhaps no operation to which the term reason is so appropriately applicable." . This proposition respecting reason is, we believe, generally acknowledged by philosophers; especially since the principles of it were so well displayed by Malebranche, who shows, in a very plausible manner, that the difference between simple perception, judgment, and reason, consists in this,?that, by simple perception, the understanding perceives a thing ?without relation to any other thing ; that, by judgment, it perceives the relations t existing between one or more things; and that, in reasoning, it perceives the relations perceived by the judgment: it is the knowledge of these relations that constitutes the faculty of adapting means to ends. But, the denial of this faculty to brutes, is a point in which many great modern, as well as ancient, philosophers, do not agree with the author. We shall pass over this question, of course, as not relating to medical logic.
The faculty of applying means to ends in the art of medicine, is a sort of knowledge that " has, to some persons of a sceptical turn of mind," the author observes, " appeared so unattainable, as not to be worth prosecuting, and they raise the previous question, an datur ars medicine The author argues in favour of its validity, from the actions of the brute creation, and of savages, when suffering disease: he remarks, that savages but rarely die of old age, though their maladies are fewer, and less essentially severe, than those of cultivated nations; he points out also, as an evidence of the reality of the medical art, the undoubted beneficial control it exerts over many diseases.
What, too, would be the use of various plants, except as medicines ? he enquires; and, finally, he says, to deny it, is to arraign the benevolence of nature, in subjecting man to the calamities of disease, without providing means for their relief. He concludes the introduction with observing, that it is his intention, ** with unfeigned diffidence and humility, to endeavour to point out, in what medical truth consists; what are the difficulties that have obstructed its progress; and what the means of obviating them." The preliminary observations to the body of the work commence with a remark, that it is the knowledge of the reciprocal relations of cause and effect, and thence the faculty of adapting means to ends, and the just application of such as we can com-300s Critical Analysis* mand^ which constitute skill and judgment in the cure of disease*, as well.as in the other arts oflciyilized life. " These agencies,".
Sir Gilbert Blane continues to state, " are ascertained by observation: and experiment; hy the former we may be said to listen to nature, by the latter to interrogate her." He conceives that there exists a certain relation between'the structure of the body and;its; qualities with the surrounding natural, ob* jects and* phenomena. " Every reflecting mind," the author says, " must be struck with the admirable correspondence olfc the structure of the living body as a whole, and of the senses and functions in detail, in relation to external nature ; suchr the adaption of the whole frame to the laws of gravitation, and* of the eye and ear to the properties of light and air.-' The author carries this sentiment further : he says there is a, similar relation existing between the constitution of the mindand the laws of nature; the most essential attributes, of these being the constancy of their operation. M Now," he continues, il the human mind has as evident a relation to this constancy of the laws of nature* as the senses have, to i their re-> spective elements; fori, from the earliest period of life, there;iSi pra? vious to all experience, a most unbounded confidenoe in the present? and future constancy, of events, manifested in all the actions and at* tainments of practical life. The belief that, the sun will continue to, rise every morning; that all bodies will continue to gravitate to the earth ; that, the human beings around us exist, feel, and think, as. we do, may be quoted as examples of this untaught knowledge." If this opinion be correct, the fable of the Sybarites, wha blinded themselves in the darkness of the first night* believing^ their eyes would in future be devoid-of use* must be considered, an idle invention, instead of being, as the doctrine of some great philosophers would lead us to interpret it, a symbolic ii-? lustration of a metaphysical truths.
Sir Gilbert Blane, proceeding in a train of reasoning on the same principles, says, But this is not all, nor the most important coincidence of the frame of the mind with the established course of nature. I*i all the effects pro?" duced by the action of external bodies on each other, and on our own> bodies, there is a rapid and instinctive connexion established between cause and effect, in, virtue of that part of the structure of the mind by> which it is made susceptible of habit and association, particularly inearly life. So that, not only every organ and function of the body,, but every faculty of the mind, is co-relative^ with) or represents antl> reflects, as it were, the elements and laws of universal nature."* * " Sec ttiis sentiment more fnlly illustrated, in a lecture on Muscular Motion, reaci het'ore the Royal Society, by Gilbert-Blane, M<d. page4& London, 17894' It is also most.ingeniously.and,appositely ajlijdqd t$,iu, Madams do count of tlnr German poet rjyiu. her work entitled D.e I'Atlefniig/ie, pagq Paris, IMS-;*' * -"?
Sir Gilbert Blane's Elements of Medical Logick.

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This dofetrine was first advanced by the author in a discourse read-to the1 Speculative Society of Edinburgh, in tfhe year I7i7 I ; and, as must be obvious, it is in opposition to that Atfhich states custom to be the only source of our ideas of cause and effect.
It was against Mr. Hume, the most forcible advocate of that doctrine, that Sir Gilbert'Blane especially made this attack. We shall not presume to adduce our opinion on a question that still divides many great metaphysicians ; but we must remark, that we think Sir Gilbert Blane, in the following paragraph, rather favours, than controverts, the notions he opposes. He says, fThese confident expectations of the future, could never have been discovered by reasonings ^prim; inasmuch as we know nothing of the tie which connects cause and effect; nor can we form any anticipations of future events, but from, the past experience of what may &e Called simple sequence." These speculations must not be considered totally foreign to the proper subject of this work, because, by reasoning directly 'or analogically from what we have been taught by custom ; or, according to the doctrine of Sir Gilbert Blane, by finding that, in imitating the -sequences of ?nature, we can 'adapt means to ends, so-as to'bring about certain result's ; we acquire our first idea of power,?the want of accuracy in which, in the 'forcible expressions of the author, " has given rise to those mischievous errors and inveterate prejudices, those nuniberless fallacies', those nugatory and superstitious practices, with which the history of the world abounds, and which have proved sources of Vice and niisery, embittering and deforming human life and conduct;" We shall not pursue this subject further than the author has 'here done ; we think, with him, that some attention to it forms a proper introduction to medical logic: but it is from treatises expressly metaphysical that the 'knowledge of lit must be ac-^qiiired.
To determine correctly the relations of causes and effects, and from'first and real principles to form rational inductions, is, as the author observes, the true object of philosophy. Thfe living ?ody being .endowed with such a multitude of properties, and, consequently, its functions being so numerous and so variable under different circumstances,cannot, without extreme difficulty, be submitted to this rational research.
But," Sir Gilbert continues to observe, <c it is incumbent tin those who allege that there are obstacles to physiological investigations, seemingly so insurmountable, to specify what fhey are. 44 The author, therefore, submits to the profession the following enumeration of the properties peculiar to animated nature j meaning Others he defines, certainly, as active principles or primary agents: let us take a view of his dissertations upon these. We transcribe the whole of what he advances respecting the first; i{ The Generative.?It will not be disputed, that this primaryenergy of nature belongs purely and peculiarly to animal and vegetable life. Being emphatically named the mystery of nature, and being now admitted, by all correct physiologists, to be inexplicable, it only requires in this place to be barely enunciated. It may not, however, be without use here to hold out as a beacon to those who may still be disposed to waste their time and labour in attempting to ' overleap the stated boundaries of nature, the fruitless and absurd re. suits they are likely to attain; for, what can be so extravagant and Irrational, as that hypothesis which professes to explain generation, by supposing an infinite involution of embryos: Obscura obscuriotibus.
The doctrine of that most respectable physiologist, Dr. Blumenbach, who refers generation and growth to what he calls the formative nisust is perfectly consistent with reason ; inasmuch as it is to be considered father as an exposition of facts than as a theory."*' We shall follow the author's judicious advice, and not waste time in enquiries whether generation should be considered as the result of the play of certain functions of organized bodies, or as the work of an intelligent energy, an archtrus, within organized bodies, moulding animal matter at its will; particularly as the subject of discussion is medical logic, on which nothing doubtful should be advanced,?nothing that is not an exposition of observed facts. Though, we must say, it is somewhat curious that we should be cautioned against enquiries on this subject, since they are likely to lead to absurd results, and immediately afterwards the doctrine of a physiologist designated as perfectly consistent with reason: whether as an exposition of facts or as a theory, does not signify ; because, if one man has been able to discern facts respecting it, another may hope to do the samp to a greater extent: and what is any knowledge but ideas of facts, or any theory but an exposition of them ?
We proceed to the consideration of the author's illustrations of the other energies.
,l The Conservative.?By this is meant that power by which the living body is prevented from running into putrefaction. According to the experiments of Dr. Alexander,! the range of temperature most * favourable to the putrefaction of dead animal matter, being between Reasoning on this must be hypothetical;?it is certainly'hypothetical to suppose the existence of an abstract1 intelligent agent in organized bodies, for the sole purpose df pres^frViag thdm from putrefaction: but it is a very probable hypothesis which attributes the preservation of living animal bodies from putrefaction, to the affinities between its particles constantly in play whilst its functions are performed. When these cestee, those bodies then become subject to the mO?e powerful affinities ck the surrounding medium, which are chemical affinities, ivhilst the particles of the dead body are kept 'together only by the Common gravitation, and the weak cohesion df sdFt sub-Stances. ' ; The author, referring to this opinion, whidi was that, 'he Says, of Dr. Alexander, and some other physiologists df that 'day, (and is that of many great physiologists of the present^ too, should have been added,) says, " It is quite inadequateito account for this striking phenomenon; and that there is an antiseptic power in life, independant of motion and the change of matter, is proved by the same principle of self-preservation being found in the quiescent state: for instance, in impregnated eggs and torpid animals." These things afford no support whatever to the iuthor's hypothesis; for it is certain that torpid animals are not in a quiescent state; and it is very proba,ble, if abstract reasoning alone can make any thing probable, that the egg is not so. The statement we have made respecting torpid animals, has been satisfactorily proved by the experiments df Professor Mangili, of Padua: he has ascertained that respiration, and of course the circulation of the blood, are slowly carried on. This might have been well supposed ; for, if there were no actions going on in them, how is the fat with which they abound before they become torpid absorbed, leaving them comparatively thin and -emaciated when they come out of that state?
And, how can the egg be supposed to be in a quiescent state ? It contains an organized mass: how can this have heen formed without action ? How is the chick subsequently developed, without action ? It is more rational to suppose that a 'degree of action, insensible to our eyes, is constantly going on in the living egg, analogous to that by which its organization "wais developed,* than that it ever totally ceases for a time, and is then resumed. Besides, why is a living egg warmer in a certain * Malpighi says, the body of the chick is formed m an egg before -the incubative heat is applied. r s 1 Sir Gilbert Bland's Elements of Medical Logick. 311 tgmper^tureofthe atmosphere than adead one? and why isjtnot? frozen in the same degree of heat ? How can the materia vita^, the existence of whiph the author favours, cause this difference in the living egg,, in any other way than by producing action ?
We are at a loss to conceive how an organized mass, in an absolutely quiescent state, can be said to be influenced by any agent. If it is influenced by it, it must be acted on by it, and,re-action must ensue. If it i? not influenced by it, we must look for other reasons for the phenomena we have alluded to; and no reason can be so satisfactory, considering the subject in an abstract manner, as that there is a series of actions going on; and analogical reasoning from observed physiological facts shows the probability of this opinion; always bearing in mind that an egg is an organized animal body: and, with respect to the want of evidence to the senses of the existence of action* living plants stand in a similar relation to them.
The author adduces some other general arguments, which we consider as still less valid than those we have noticed, in favour of the existence of a materia vita, the original invention of which doctrine he attributes to John Hunter; and he expresses, his surprise that " we meet with works on physiology, some of them even professing to be complete systems, in which this fundamental law of life is not alluded to." Here we do not comprehend what the author means to sig-, nify: terming the existence of a principle, supposing it were not suppositious, a law of life, is using language in a manner so different from its common acceptation, that we cannot at, all understand it.
We must make some remarks respecting the neglect of this doctrine ofthe existence of a materia vita.
It is not admitted, either because it is considered that the cause of life cannot be regarded in an abstract manner, as distinct from organization; or because tjbe admission of such a principle is, at least, contrary. to'the mode of philosophizing inculcated by Bacon.
We here pass over the assimilative and temperative energies^ because, as we have already shown, the author defines them, substantively, heat and assimilation, and states these to be. results of the functions of the system. " The Formative.?This may be called also the organizing or fjlastlc.
It has not usually been stated as a principle distinct from the. ast, (the assimilative.) The slightest "reflection, however, must evince that it is quite a separate act of nature, and as different from, the assimilative as the construction of an edifice is from the preparation ^nd collection of its materials." It is by this, the author says, that the processes of growth and repair are effected; and, as a subject far wonder, " with, sucty. 3l2 Critical Analysis, harmony on both sides the body, as to produce that correspondence and symmetry which we behold !'* " This is a subject," the author continues, " the nature of which eludes the keenest research, and overwhelms the mind of man with astonishment and despair; from which it can find no refuge, but in resting on it as an ultimate fact, and referring the whole to supreme intelligence.'* s .....

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In the latter sentiment we most cordially concur, but not in the former of those contained in the foregoing paragraph. We have, happily for our mental comfort, ceased to feel despair at riot being able to discover the proximate cause of any natural phenomenon ; but we know what it is to experience this suffering, and we yet remember it with pain. In early life, before we had studied the works of Bacon, or become acquainted with the disputes of the Academic sect, as may well be supposed, we endeavoured to discover the cause of apparently one of the most simple of natural phenomena,?the passing of a ball from the hand of a person in a direction different from that which it would take when solely influenced by the laws of gravitation. Our books told us that momentum was given to it. But what is momentum? Is it something material, or is it immaterial? and how can it act on the ball after this has left the hand ? We were indeed "overwhelmed with astonishment and despair.'* The hints these remarks convey may prove useful to some of our younger readers.
Returning to the author's dissertation on the formative energy, we find him remark, in continuation from the paragraph last transcribed, that, " Should any one attempt to scan it further, by ascending higher in the scale of natural causes, (higher than supreme intelligence?) he will either find himself baffled, or will be in hazard of falling into some extravagance ; such as that of Van Helmont, who held that there was in living beings an intelligent principle, which he called Archaeus^ presiding over, and directing, the secret movements of the animal ma> thine; or of Stahl, who referred it to the rational soul." We revere Van Helmont; and regret to see his opinions marked with the stigma of blame, without their merits being at the same time designated. His accurate and penetrative views led him to discern that there must be an active and powerful influence, seated about the region of the stomach, distinct from the other chief influences regulating the functions of the system; that is, distinct from the brain and spinal marrow. The functions of the ganglionic system of nerves had not then been de, termined by experiments; this was not effected until nearly a century after, by James Johnstone : but Van Helmont had in i manner anticipated the discovery j and the making that in-?
Sir Gilbert Dane's Elements o f ^/e die a I Logick. finance consist in air intelligent immaterial principle, was, with, a few chemical absurdities, as $ir Gilbert Blane indeed observes, the error of his age. Put the ganglionic system of nerves iu the place of his arc/ieeus, and his works must be perused witli benefit and delight. We proceed with the transcription of another paragraph : ii The proper function of the formative faculty, is growth and repair. The long and universally received mode of conceiving the progress of growth, was that of a constant accretion of organic matter, giving additional length and breadth to the parts nourished. But it is evident that this would render the preservation of shape utterly in^ compatible with the enlargement of dimension ; and it was first clearly demonstrated by Mr. John Hunter, that the only process by which the growth of solid parts, particularly bones, could be carried ou, was by a constant removal and replacement of particles." Here we must correct a little error in the history of physiological opinions. It may be difficult to determine when the longer be the same man, is very ancient. However, this doctrine is fully and accurately displayed by Bordeu ; and we particularly not,ice this, because we can at.the same time refer to an author who dwells with much earnestness on some pathological notions, which Sir Gilbert Blane also advances as worthy of consideration : that there seem to be particular outlets for particular species of effete matter. Bordeu has perhaps carried this doctrine to excess, in his endeavours to rescue the physiology of the human body from the dominion of the chemists and mechanists, in that curious specimen of fervid discussion, his Analyse Aledicinale du Sang.
On the restorative energy, the author observes, " it i's well remarked by Dr. Gregory,* that it carries in itself the means of repairing the injuries and disorders incident to it." The chief illustrations of this which the author adduced, are the phenomena attendant on sleep ; several very curious and interesting facts respecting which he adduces; and its agency, as the vis medicatrix natura.
Whether the phenomena last alluded to depend on an abstract intelligent principle, or are results of the common laws of Critical Analysis, the animal economy, is a question likely to be a subject of sefrow lastic disputation for a long period to come. We shall certainly not attempt to discuss it, whilst the works of Boyle and Glisson are in existence.
The motive, the sensitive, and the sympathetic, energies, we shall here passover; because, as we have already observed respecting the two former, the author defines them as results of the functions of the system.
Here we arrive at the termination of the first section of this Work ; and we repeat, we are by no means certain that we have seized the precise meaning of the author respecting the ti ultimate facts, or primary elements, which form the groundwork of physiological and pathological science,'* not founded on an enumeration of functions. We have some conception that he may intend, by these energies, only to designate phenomena resulting from the exercise of the functions, but which are not themselves the functions: in other words, that these are an analysis of the functions. But then, his express language does not authorize such a supposition ; on the contrary, it, with regard to some of them, designates those energies as species of abstract intelligent agents existing in the animal body,, each having its peculiar office, and exerting its influence on ianimal matter in virtue of its will, if it may be so expressed* And, if by these energies it is intended, as we have supposed^ to designate an analysis of the functions, then there is nothing whatever of novelty in what the author ha's adduced, as far as relates to principles ; though his illustrations of them, regarded in the point of view last alluded to, are often original and ingenious.
No work ever passed our critical examination that we have been so desirous to press on the perusal Of our readers, as the one before us. The reason of this must be too obvious to require explanation. This work has been produced, the author states in a preface, in consequence of Mr. A. Cooper having offered to the gentlejnen educated at the school of Guy and St. Thomas, a prize for the best dissertation on the Blood. <? I instituted some experiments on the subject," he continues to observe, " and stated the results which my observations afforded. This essay being, so fortunate as to obtain the prize, I have been induced to pre-Mr. Thackrah on the Nature and Properties of the Blood. S I 5 sent it to the public : and, since the late period at which I heard <of Mr. Coopers proposal prevented the Inquiry's comprehending, in the first instance, some points of importance, I have, during the last year, been endeavouring to supply the ?deficiency." We have not often perused a work to which we could give more unqualified approbation. Extensive and sound erudition, great accuracy in all the necessary observations and experiments, comprehensive views, and a particular clearness of exposition, mark the character of the work ; and, what is of especial importance, and which renders it interesting beyond the merely physiological relations of the subject, the author has seized every opportunity of making researches tending to the improvement of the practice of medicine ; and he has adduced from them several novel and highly-useful observations, which he has illustrated by his judicious remarks.
The circumstances of this being a successful prize-disserta-? tjon, and the subject being one respecting which a new and comprehensive treatise was so much required, deduced from researches after facts, uninfluenced by any preconceived hypothesis, will, we feel confident, induce medical practitioners in general to become possessed of the work: we shall therefore pass over in a rapid manner the chief part of it, that we may fiotice more at length that which is especially applicable to th$ practice of medicine. An abstract of this may prove a fertile source of reference, on various important occasions.
After soipe general observations on the origin, character, and uses of the blood, the author notices its most remarkable physical characteristics: and, first, its coagulation on removal from the body, and its change from a homogeneous fluid to the division into the serum and crassamentum. Its proportion to the weight of the body, is next considered. " Keil," the authpr observes, " estimated it at one hundred pounds ; others do not believe it to exceed eight pounds, Haller computes it at ten j Young at forty; and, in Cooper's lectures, its proportion to the solids of the body, is considered as one to sixteen or twenty." Eight or ten pounds, he justly remarks, must be concluded too small a quantity for the supply of the numerous vessels of the body, occupying so extensive a space; and, indeed, it seems to be shown by the quantity lost within a few days, spontaneously or abstracted by art, being frequently greater than that, without the destruction of life.
The question of the vitality of the blood, is next briefly discussed ; which the author is disposed to decide in the negative. The arguments he adduces to this effect, are novel and ingenious.
The advocates of the affirmative are, we believe, becoming daily less numerous. 2 s 2 316 Critical Analysis. On the subject of the chemical qualities of the blood, nq prigihal observations aje adduced.
The next chapter is on the peculiarities of the blood in different classes of animals. The ftuthor first confirms the statement of former physiologists, that there is but little variation of its character in those of the higher orders. The relative quantity. was found, generally speaking, to be less in birds, fishes, and the weaker animals, than in the larger and more muscular.
No uniform disparity was found to exist in the relative quantities of the serum and crassamentum; but, the author states, it appears probable, that a more complete examination would prove the crassamentum to bear a proportion to the strength and ferocity of the animal." With respect to the periods of coagulationy " a general inference might be drawn, that coagulation commences sooner in small and weak animals, than in the large and strong." ' Its tempefatui e in the horse, when flowing hiatter, and a larger proportion of azote, than that of man. Its Specific gravity is nearly uniform. "The red globules exist principally in the more perfect animals: in the mammalia and birds, partly in fishes; but not generally in reptiles, insects, and worms. In some creatures, coloured blood is found in the vessels near the heart, while the rest of the body is supplied only with a serous fluid." " Of those creatures which want the red particles, most have white globules; but, in the lowest orders, even these cannot be discerned by the microscope.'* The blood of some animals is found, while circulating, to contain air-bubbles. In the land and sea tortoises, in some fish, in the hedge-hog, and the viper, this appearance has been asserted by respectable writers.?Morgagni, ?p. v. 22. The coagulation of the blood is then particularly discussed. On t! lis subject we find some original observations, possessing a considerable degree of interest. The author first notices the effects of chemical agents mingled with it on removal from the body. Medicines, internally administered, had no apparent influence on it.
Stupefaction from opium does not affect it. It is induced readily, in proportion to its paucity. Agitation retards it. Vyith respect, to temperature, it concretes soonest at from 100??120? ; next at from 40p?30u; and last, and with a greater disparity, in that of from 60? to 90?. And the author thinks it worthy of remark, that the serum is most readily anjd copiously effused in the higher temperatures'j and this, he believes, In regular gradation, v Mr. Thackrah on the Nature and Properties of the Blood. SIT A subject which particularly engaged the authors attention, is the comparative periods of coagulation, as influenced by the strength or "weakness of the vascular action. From various and repeated experiments, under different circumstances, on the blood of oxen, sheep, horses, dogs, and swine, it appears that the blood coagulates slowly, in regular proportion to the tonic state, or that condition of the system in which the vital powers are strongest. It also appeared, that coagulation occurred soonest in venous blood.
The causes of the blood"1s coagulation constitute one of the most interesting-parts of the enquiry ; and it has been investigated bj' Mr. Thackrah with care and attention proportionate to its importance. We shall only adduce his conclusion respecting them; remarking, at the same time, that his grounds for it appear to be satisfactory, though we are unable to form any rational explanation of this phenomenon. It is " that the vital or nervous influence, is the source of the blood's fluidity ; and its loss, the cause of coagulation." But this conclusion, it must be observed, applies to the vessels in which it is contained, not to the fluid itself. Indeed, the series of experiments that led the author to form this conclusion, appear to us to furnish very powerful arguments against the doctrine of the vitality of the ^)lood.
The above opinion of Mr. Thackrah, we should remark, is similar to one advanced several years since by Mr. Charles Bell, in his Anatomical Lectures; and was then, we believe, considered to be merely visionary by many of his auditors.
But the experiments of Mr. Thackrah seem almost to demonstrate its truth.
VYe now arrive at the chapter treating of the changes produced by disease. After some reflections on the degree of importance and certainty attached to them, the author treats of the quantity of the blood. This is a subject on which ouly probable suppo-